Expressway S2 tunnel in Warsaw
The 343rd longest tunnel in the world
Expressway S2 is a short highway in Poland, serving as the southern section of the (partially completed) Warsaw Express Ring Road. Conceptually forming one continuous route with motorway A2, it was initially planned (since 1970s) as a part of it, however after local Warsaw residents objected to the plans of an inner-city motorway, the proposed road was downgraded to an expressway (though the actual route was not changed). The western half of the road was opened to traffic in 2013, while the eastern half was opened in 2020 and 2021.
Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).